Just a side-note:You can take clean screen grabs directly to USB thumb drive by pressing the green printer button (below "Help").So you do not have to fiddle around with a camera while probing etc.The thumb drive needs to be FAT32 or FAT16 formatted, there are reports on some drives that just don’t want to work, it is recommended to use a drive of 8Gb or smaller (my unit has no problems with 128Gb, but who knows).

How are you connecting the probes? Can you connect both ground clips to the exact same point on the device under test? If the ground clips are at different points on a PCB then that sort of signal is very likely.

It could also be radio noise from switching. Using the spring clips can help with that. If the peaks are reduced in size when you use a spring then that's probably the explanation.

This is my first oscilloscope so I'm not sure if this is expected behaviour or if there is something wrong with the scope.

In this example I am looking at two signals from an ESP32 development board.

When I have the lower signal probe disconnected at from the ESP32 board the top signal looks ok.

When I connect the lower signal probe to the ESP32 the signal seems to interfere with the top signal.

When I disconnect the lower signal probe from the oscilloscope but not from the ESP32 board I still see this interference.

Could someone please explain what might be going on here as I'm a bit confused!

All the best

Andy

Try just connecting the yellow signal by itself and work on improving the probe's ground connection until you get a cleaner signal without the overshoot spikes. (The shorter and more secure the ground connection between the probe and the DUT the better.)

As for the blue signal showing interference even when the yellow probe is disconnected from the scope, if that is occurring when the yellow probe remains attached to the DUT, it would seem to indicate the yellow probe is picking up RF from something or otherwise contributing to the interference. (Presumably, the interference on the blue signal goes away when you disconnect the yellow probe not only from the scope but also from the DUT?)

It looks like these might be two separate issues, although perhaps if the probe ground connection is better made for the yellow signal (and maybe also for the blue signal) it might help reduce the interference impacting the blue signal. Fixing the yellow ground issue should be relatively easy, fixing the blue interference issue might take more work.

This is my first oscilloscope so I'm not sure if this is expected behaviour or if there is something wrong with the scope.

In this example I am looking at two signals from an ESP32 development board.

When I have the lower signal probe disconnected at from the ESP32 board the top signal looks ok.

When I connect the lower signal probe to the ESP32 the signal seems to interfere with the top signal.

When I disconnect the lower signal probe from the oscilloscope but not from the ESP32 board I still see this interference.

Could someone please explain what might be going on here as I'm a bit confused!

All the best

Andy

It looks more like a grounding / power supply problem on the DUT (ESP32 board) than a noise problem on the scope. There is a lot of ringing on the signal. What are the signals being probed? Maybe the crosstalk is already present on the ESP32 board and the scope is capturing exactly what is happening on the DUT.

This is my first oscilloscope so I'm not sure if this is expected behaviour or if there is something wrong with the scope.

In this example I am looking at two signals from an ESP32 development board.

When I have the lower signal probe disconnected at from the ESP32 board the top signal looks ok.

When I connect the lower signal probe to the ESP32 the signal seems to interfere with the top signal.

When I disconnect the lower signal probe from the oscilloscope but not from the ESP32 board I still see this interference.

Could someone please explain what might be going on here as I'm a bit confused!

All the best

Andy

It looks more like a grounding / power supply problem on the DUT (ESP32 board) than a noise problem on the scope. There is a lot of ringing on the signal. What are the signals being probed? Maybe the crosstalk is already present on the ESP32 board and the scope is capturing exactly what is happening on the DUT.

Agreed. I think the issue was amplified/masked by the probe grounding technique; now that Andy has that pretty well squared away, the noise level is relatively lower. The videos with information on scope settings were just to show that it's sometimes possible to fine tune the view into the noise. Whatever noise is left might either be a non-issue for the DUT's performance, or if it is, it might be due to a further grounding and/or power supply problem on the DUT. It's a matter of peeling things back depending on the level of subtleties that need to be examined. To me this is the part of the intrinsic enjoyment of test equipment - test equipment not only helps people measure, design, build, test, debug, and repair but in the process it helps people learn by visualizing relatively small, subtle, and otherwise difficult to observe phenomena.

The original images I posted were probed from a breadboard connected by 6 inch jumper cables to the ESP32 board with the probe grounds also connected to another 6 inches of jumper wire so 12 inches in total.

I now know if you want more accurate results this isn't a good idea.

If I probe directly off the pins on the board using the spring ground everything cleans up well.

Originally I was using it to look at 4 pins of 20Mhz SPI and the interference was causing problems with the decoding, I have since worked out how to change the logic trigger levels of the SPI decoder on the scope to get over this problem.

I haven't checked if using the spring ground directly to the board pins will clean up the ringing, I will have a look in the morning.

The help and videos posted here have helped me understand a lot more about what is going on, now I know there is nothing wrong with the scope, it was only my ignorance getting in the way!

What would be quite useful is some attachment for the end of the probe that split out the probe and ground onto short wires with pincers, I'm on the lookout for some if I can't find anything I guess I can knock something up. This would get over the problem with the springs of needing an earth near what you want to probe.

The original images I posted were probed from a breadboard connected by 6 inch jumper cables to the ESP32 board with the probe grounds also connected to another 6 inches of jumper wire so 12 inches in total.

What would be quite useful is some attachment for the end of the probe that split out the probe and ground onto short wires with pincers, I'm on the lookout for some if I can't find anythind I guess I can knock something up. This would get over the problem with the springs of needing an earth near what you want to probe.

The original images I posted were probed from a breadboard connected by 6 inch jumper cables to the ESP32 board with the probe grounds also connected to another 6 inches of jumper wire so 12 inches in total.

I also use breadboards for early prototypes / tests, but try to use male pin headers to create scope/logic analyzer hookup points and it gives better results than flexible jumper wires.

Originally I was using it to look at 4 pins of 20Mhz SPI and the interference was causing problems with the decoding, I have since worked out how to change the logic trigger levels of the SPI decoder on the scope to get over this problem.

What would be quite useful is some attachment for the end of the probe that split out the probe and ground onto short wires with pincers, I'm on the lookout for some if I can't find anything I guess I can knock something up. This would get over the problem with the springs of needing an earth near what you want to probe.

Your idea might make a very useful product or tool if it could be designed/made. Let us know what you come up with.